This invention relates to coatings having unique electrical properties, and is particularly concerned with improved coatings having lightning protection and anti-static properties primarily for application to aluminum in aircraft structures, such coatings containing additives which increase the electrical conductivity of the paint to the metal, e.g. aluminum substrate.
Prior methods for dissipating electrical charges on aircraft skins, e.g. produced by lightning and particle friction which build up on painted aluminum aircraft surfaces, have not been entirely satisfactory.
Static dischargers are generally placed on commercial and military aircraft to quietly discharge the aircraft's electrical charge build-up. Although the presently employed dischargers are small, they increase drag, weight and cost of maintenance.
In addition, many aircraft incidents involving fuel tank fires and resulting in minor explosion during ground refueling or purging, have occurred. The latter incidents are attributed to electrostatic discharges within the fuel tanks.
Thus, currently employed aerospace or aircraft coatings do not provide completely effective lightning and anti-static protection on thin fuel tank skins, radomes, windshields, leading edges of aircraft, and the like.
It is one object of the present invention to provide an efficient organic coating with unique electrical properties which do not disturb the original properties of the coatings. Another object is the provision of an additive for organic paints and coatings, e.g. polyurethane or fluoroelastomer paints, which substantially increases the electrical dispersing properties of swept stroke lightning currents and substantially reduces the dielectric strength of the coating, particularly when applied to a metal or non-metal aircraft skin, to thereby rapidly dissipate such swept stroke currents or prevent build-up of electrostatic charges on the coating. A still further object is to afford an improved lightning protection and anti-static organic paint or coating having the above desirable characteristics, and including increased electrical conductivity, erosion and abrasion resistance and strength, without interfering with or reducing the desired favorable protective properties of the organic coating.